1. Field of the Invention
The present invention relates to an antitheft device and an antitheft method and, more particularly, to an antitheft device and an antitheft method for preventing incidents such as vehicle theft and theft from a vehicle.
2. Description of the Relevant Art
Both the number of cases and the incidence of incidents such as vehicle theft and theft from a vehicle are tending upward. Therefore, in recent years, various antitheft devices for preventing vehicle theft and theft from a vehicle have been proposed (for example, Japanese Kokai No.1998-44937, and Japanese Utility Model Application No.1993-35518 and No.2002-79911).
FIG. 6 is a block diagram schematically showing the principal part of an antitheft system comprising a conventional antitheft device. Reference numeral 1 in the figure represents an antitheft device having a function of door locking control by remote operation, comprising a microcomputer 2, an antenna 3 and a receiving section 4 for receiving signals sent from a portable transmitter 21, and an EEPROM 5 in which an ID code is stored.
To the antitheft device 1, a key insertion detector 6 for detecting whether an ignition key has been inserted in a key cylinder, a door opening/closing detector 7 for detecting the open/closed state of doors, a trunk opening/closing detector 8 for detecting the open/closed state of a trunk lid, a door locking detector 9 for detecting the locked/unlocked state of the doors, a door lock actuator 10 for locking/unlocking the doors, an intruder detector 11 for detecting an intruder into a vehicle and an audible alarm generator 12 for generating an audible alarm are connected. Here, as the intruder detector 11, a vibration sensor for detecting breaking of glass, an ultrasonic sensor for detecting a motion of a person who intruded into the vehicle, a tilting sensor for detecting a tilt of the vehicle and a sensor for detecting a decrease in voltage of a battery are exemplified.
The portable transmitter 21 comprises a microcomputer (not shown), an antenna 22 and a transmitting section (not shown) for transmitting a prescribed signal to the antitheft device 1, an EEPROM (not shown) in which an ID code is stored, and button switches 23 and 24 for instructing to lock and unlock the doors by remote operation, respectively.
When the button switch 23 is pressed, the microcomputer of the portable transmitter 21 sends a signal including the ID code and a door locking command code through the antenna 22 to the outside. On the other hand, when the button switch 24 is pressed, the microcomputer thereof sends a signal including the ID code and a door unlocking command code through the antenna 22 to the outside.
When receiving a signal instructing to lock the doors from the portable transmitter 21 being carried by its user, the antitheft device 1 judges whether the signal is proper or not (or whether the signal is not sent from any transmitter other than the portable transmitter 21). When the signal is judged to be proper, all the doors are locked by controlling the door lock actuator 10 and the like and an arming mode for being on the alert for theft is set. At that time, in a case where all the doors and the trunk lid are closed, all the doors being in the locked state when a preset delay time (e.g. 20–30 seconds) has elapsed since the necessity to set the arming mode was determined, the arming mode is set. Here, the reason why the arming mode is set when the prescribed time elapsed after door locking control is that it is supposed that there is a fellow passenger who gets out of the vehicle after the user (being a driver in most cases) who operates the portable transmitter 21.
When the arming mode is set, monitoring of an unauthorized action is started. When an unauthorized action is detected, an audible alarm is generated by controlling the audible alarm generator 12 and the like. For example, when opening of a door or the trunk lid, breaking of glass, a tilt of the vehicle or removal of the battery (or a decrease in battery voltage) is detected, an audible alarm is generated.
When receiving a signal instructing to lock the doors by key operation, the antitheft device 1 controls the door lock actuator 10 and the like so as to lock all the doors and sets the arming mode in the same manner as the above. Likewise, in a case where all the doors and the trunk lid are closed, all the doors being in the locked state when the prescribed delay time has elapsed, the arming mode is set.
By the way, recently, as to not only door locking but also engine starting, remote operation has been realized (for example, Japanese Utility Model Application No.2002-79911, Japanese Kokai No.1997-256932 and Japanese Utility Model Application No.1997-329075). The realization of engine starting by remote operation has an excellent effect that the vehicle environment can be made comfortable by a warm-up before getting-on.
In cases where such remote operation for instructing to start the engine is conducted, the user is often away from the vehicle. Therefore, if the engine is started by remote operation in a state where the arming mode has not been set, for example, in a case where the user carelessly conducted an unlocking operation in conducting an engine start by remote operation, the risk of suffering vehicle theft becomes extremely high. Therefore, it becomes important that the arming mode is also set in the case of the engine being started by remote operation.
However, in a conventional antitheft device, even in the case of engine starting by remote operation (or although the vehicle is often unoccupied and no passenger gets out of the vehicle when the engine is started by remote operation), the arming mode is set after an elapse of a delay time preset in consideration of a fellow passenger's getting-off, similarly to the case of setting the arming mode after door locking using a portable transmitter or by key operation.
When an engine start by remote operation is conducted with putting/taking luggage into/out of the trunk in the state of the trunk lid being opened after the doors of the vehicle were unlocked (or after the arming mode was canceled), the arming mode is not set in some cases. Moreover, when the engine is started, the vehicle creates vibrations or something. Therefore, if an alert status in the arming mode being set in the case of receiving a remote operation for instructing to start the engine (such as detected subjects for detecting an unauthorized action or the detection sensitivity for detecting the unauthorized action) is the same as an alert status in the arming mode being set in the case of receiving a door locking operation, a vibration sensor or the like as a theft detector reacts thereto, resulting in an inconvenience.